Method and module for measuring rotation and portable apparatus comprising the module

ABSTRACT

The invention discloses a method and a module for measuring rotation and a portable apparatus comprising said module. The module of the present invention is adapted for measuring rotation of a target, and the module includes a first sensor, a second sensor and a processor. The first sensor is disposed at a first location of the target, for sensing a first centripetal acceleration and a first tangential acceleration when the target is rotated. The second sensor is disposed at a second location of the target, for sensing a second centripetal acceleration and a second tangential acceleration when the target is rotated. The processor is coupled to the first sensor and the second sensor, for receiving the first centripetal acceleration and the first tangential acceleration from the first sensor, receiving the second centripetal acceleration and the second tangential acceleration from the second sensor, and calculating the rotation angle of the target accordingly.

FIELD OF THE INVENTION

The present invention relates to a method and module for measuringrotation and portable apparatus comprising of the module, and itspecifically relates a method and module for measuring rotation usingonly three axes accelerometer and portable apparatus comprising of themodule.

BACKGROUND OF THE INVENTION

Portable electronic devices, for example, mobile phone, notebookcomputer, tablet computer, personal digital assistant and media player,have more and more functions, and the users have more dependence onportable electronic device, that is, lots of daily work or job relatedbehavior have to rely on the assistance from portable electronic device.For example, for current mobile phone, in addition to calling andmessage sending function, usually one or several functions areintegrated, for example, photography, positioning, navigation, internetsurfing and game, etc.

In order to reach the above mentioned functions and to satisfy thedemand of the users, currently, there are lots of portable electronicdevices in the market integrating with all kinds of functional devicesor modules. For example, in order to possess photography function, lensmodule is integrated; in order to possess positioning or navigationfunction, GPS positioning module is integrated; in order to haveinternet surfing function, wireless network module is integrated; inorder to have game playing function, touch sensor and three axesaccelerometer, etc. are integrated.

Wherein, three axes accelerometer can detect the acceleration on threeaxes (that is, X, Y and Z axes) of portable electronic device, then theuser's action is reflected to perform corresponding control, forexample, the turning and velocity change of the target under control inthe game.

In the traditional three axes accelerometer, it is used to detect theincluded angle change between acceleration and gravitationalacceleration of object (for example, the above mentioned portableelectronic device), then the tilting angle generated while the objectrotates can be calculated, and corresponding control can then beperformed. However, when the rotation is not related to gravitationalforce (for example, the rotation in the horizontal direction), a singlethree axes accelerometer will be unable to measure the rotational anglechange, which might lead to inconvenience to the user.

In order to solve this issue, in addition to three axes accelerometer,the designer or the manufacturer even integrates extra component, forexample, gyroscope or digital compass to detect the horizontal rotationof the portable electronic device. However, the integration of theseextra components will increase the volume, manufacturing cost andcalculation complexity of the portable electronic device.

SUMMARY OF THE INVENTION

Therefore, the scope of this invention is to provide a method and modulefor measuring rotation and portable device comprising the module so asto solve the prior art issue.

According to one preferred embodiment, the rotation measuring module ofthis invention can measure the rotation of the target object, and therotation measuring module comprising of first sensor, second sensor andprocessor.

A first sensor is installed at the first location of the target objectso as to sense the first centripetal acceleration and the firsttangential acceleration while the target object is rotating. A secondsensor is installed at the second location of the target object so as tosense the second centrifugal acceleration and the second tangentialacceleration while the target object is rotating.

In addition, the process is connected respectively to the first sensorand the second sensor. The process can receive the first centripetalacceleration (a_(C)) and the first tangential acceleration (a_(T)) fromthe first sensor and receive the second centrifugal acceleration and thesecond tangential acceleration from the second sensor. Processor furtherfollows the following equation 1 and 2 to calculate angular velocity (ω)and angular acceleration (α) of the first location and the secondlocation:

$\begin{matrix}{\omega = \sqrt{\frac{a_{C}}{r}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\{\alpha = \frac{a_{T}}{r}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$

Wherein, r is the distance of first location and second locationrespectively to the rotational center of the target object.

Then the processor will follow the following equation 3 to calculate therotational angle (Δθ) of the target object:

$\begin{matrix}{{\Delta \; \theta} = {{{\omega \cdot \Delta}\; t} + {\frac{1}{2}{\alpha \cdot \Delta}\; t^{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$

Wherein Δt is the sampling period of first sensor and second sensorduring the measurement.

According to another preferred embodiment, the rotation measuring methodof this invention is applicable to the measurement of the rotation ofthe target object, which includes the following steps: (a) During therotation of the target object, the first centripetal acceleration andthe first tangential acceleration is measured at the first location ofthe target object, and at the second location of the target object,second centrifugal acceleration and second tangential acceleration ismeasured; (b) First centripetal acceleration(a_(C)) and first tangentialacceleration(a_(T)) is received respectively, and second centrifugalacceleration and second tangential acceleration is measured respectivelytoo; according to the above equation 1 and 2, the angular velocity (ω)and angular acceleration (α) of first location and second location arecalculated respectively; and (d) According to the above equation 3, therotational angle (Δθ) of the target object is calculated.

According to further one preferred embodiment, portable device of thisinvention includes rotation measuring module as mentioned above tomeasure the rotation of the portable device.

Since this invention uses two sensors to measure respectively thecentrifugal acceleration and tangential acceleration at differentlocations of the target object, hence, it can measure the horizontalrotation of target object. In addition, data measured by two sensors,depending on the real situation, can be mutually compensated, and theerror can be correspondingly reduced. In addition, this invention,through two sensors, can measure the horizontal rotation of the targetobject, hence, it can be integrated into the portable device, and itwill have advantages such as small volume, low cost and lowcomputational complexity, etc. as compared to the prior art technology.

For the advantages and spirit regarding the present invention, furtherunderstanding can be achieved through the following detailed descriptionand attached drawings of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A illustrates the functional block diagram of rotation measuringmodule of one preferred embodiment according to this invention.

FIG. 1B illustrates the measurement using the rotation measuring module.

FIG. 1C illustrates the sensing of rotation measuring module of thisinvention while target object is rotating.

FIG. 2 illustrates the block diagram of rotation measuring method of onepreferred embodiment of this invention.

FIGS. 3 to 5 illustrates different rotational situations of targetobject.

FIG. 6 illustrates the functional diagram of portable device of onepreferred embodiment according to this invention.

DETAILED DESCRIPTION OF THE INVENTION

This invention provides a method and module for measuring rotation and aportable device comprising of the module. In the following, through thedetailed description of preferred embodiment and actual application caseof this invention, the feature, spirit and advantages of this inventionare fully described.

Please note that the “portable device” as described in this inventioncan be, but not limited to, for example, mobile phone, personal digitalassistant, smart mobile phone, multi-media player, game box, monitor,electronic watch, measurement device, and other suitable portableelectronic device.

Please refer together to FIG. 1A, 1B, 1C and 2. In FIG. 1A, itillustrates the functional block diagram of rotation measuring moduleaccording to one preferred embodiment of this invention; FIG. 1Billustrates the measurement of the rotation measuring module; FIG. 1Cillustrates the sensing of the rotation measuring module while thetarget object is rotating; FIG. 2, illustrates the flow chart ofrotation measuring method according to one preferred embodiment of thisinvention.

As shown in FIG. 1A and 1B, the rotation measuring module 1 of thispreferred embodiment includes first sensor 10, second sensor 12 andprocessor 14. First sensor 10 is installed at the first location A oftarget object 2, and second sensor 12 is installed at the secondlocation B of target object 2. First sensor and second sensor can bethree axes accelerometer, but is not limited to this.

When target object 2 rotates, first sensor 10 can, at first location A,sense first centripetal acceleration (a_(C1)) and first tangentialacceleration (a_(T1)), and second sensor 12 can, at second location B,sense second centrifugal acceleration (a_(C2)) and second tangentialacceleration (a_(T2)) (Step S50).

Process 14 is connected respectively to first sensor and second sensor12 so as to receive from first sensor 10 the first centripetalacceleration (a_(C1)) and first tangential acceleration (a_(T1)), andreceive from second sensor 12 the second centrifugal acceleration(a_(C2)) and second tangential acceleration (a_(T2)) (Step S52). Process14 further follows the following equation 1-1 and 2-1 respectively tocalculate angular velocity (ω₁) and angular acceleration (α₁) of firstlocation A:

$\begin{matrix}{\omega_{1} = \sqrt{\frac{a_{CI}}{r_{1}}}} & \left\lbrack {{Equation}\mspace{14mu} 1\text{-}1} \right\rbrack \\{\alpha_{1} = \frac{a_{T\; 1}}{r_{1}}} & \left\lbrack {{Equation}\mspace{14mu} 2\text{-}1} \right\rbrack\end{matrix}$

Wherein, r₁ is the distance from first location A to the rotationalcenter O of target object.

In the mean time, processor 14 also follows the following equation 1-2and 2-2 to calculate respectively the angular velocity (ω₂) and angularacceleration (α₂) of second location B:

$\begin{matrix}{\omega_{2} = \sqrt{\frac{a_{C\; 2}}{r_{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 1\text{-}2} \right\rbrack \\{\alpha_{2} = \frac{a_{T\; 2}}{r_{2}}} & \left\lbrack {{Equation}\mspace{14mu} 2\text{-}2} \right\rbrack\end{matrix}$

Wherein, r₂ is the distance from second location B to the rotationalcenter O of target object (Step S54).

In real application, when r₁ and r₂ is the known given value (Forexample, when target object 2 has single rotation center, such assupport point), then the above equation can be followed to calculaterespectively angular velocity (ω₁, ω₂) and angular acceleration (α₁, α₂)of first location A and second location B. When r₁ and r₂ is unknown,processor 14 will follow the following equation 3-1 and 3-2 to calculaterespectively r₁ and r₂.

$\begin{matrix}{r_{1} = \frac{D \cdot a_{T\; 1}}{a_{T\; 1} + a_{T\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 3\text{-}1} \right\rbrack \\{r_{2} = \frac{D \cdot a_{T\; 2}}{a_{T\; 1} + a_{T\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 3\text{-}2} \right\rbrack\end{matrix}$

Wherein D is the distance between the first location A and the secondlocation B. Through this, processor 14 can also calculate the locationof rotational center O on target object 2.

Next, processor 14 can follow respectively the following equations 4-1,4-2 and the above calculated angular velocity (ω₁, ω₂) and angularacceleration (α₁, α₂) to calculate respectively the rotational angles(Δθ₁, Δθ₂) of target object 2 measured at first location A and secondlocation B:

$\begin{matrix}{{\Delta \; \theta_{1}} = {{{\omega_{1} \cdot \Delta}\; t} + {\frac{1}{2}{\alpha_{1} \cdot \Delta}\; t^{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 4\text{-}1} \right\rbrack \\{{\Delta \; \theta_{1}} = {{{\omega_{1} \cdot \Delta}\; t} + {\frac{1}{2}{\alpha_{1} \cdot \Delta}\; t^{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 4\text{-}2} \right\rbrack\end{matrix}$

Wherein Δt is the sampling period of first sensor 10 and second sensor12 during the measurement (Step S56).

From the figure, it can be seen that theoretically, when rotationalcenter O is between the first location A and the second location B,rotational angles (that is, Δθ₁, Δθ₂) of target object 2 measured atfirst location A and second location B should be equal. However, inpractice, the deviation caused by noise or different environment factorsmight lead to different rotational angles measured at first location Aand second location B.

Therefore, as shown in FIG. 1A, the rotation measuring module 1 of thispreferred embodiment can further include low pass filter 16, which can,depending on the real situation, be disposed in between first sensorand/or second sensor 12 and processor 14, and depending on the actualneed, the quantity of low pass filter 16 can be adjusted. Through theinstallation of low pass filter 16, the noise sensed by first sensor 10and/or second sensor 12 can be filtered out so as to reduce theinterference of processor 14 by noise and to calculate more accurateparameters and rotational angles. Of course, the rotation measuringmodule 1 of this invention can further includes other types ofcomponents (For example, nose inhibition component) to achieve the abovementioned objectives.

In addition, in practical application, in addition to the abovementioned noise filtering or inhibition components, the rotationmeasuring module 10 of this invention can perform data compensationthrough the following method:

First, first sensor 10, on at least two different time points, willsense at first location A the first previous data and the first nextdata, in the mean time, second sensor 12, on at least two different timepoints, will sense at second location B the second previous data and thesecond next data. Next, processor 14 will compare the first differencebetween the first previous data and the first next data, and it willalso compare the second difference between the second previous data andthe second next data. When the first difference value is larger than thedefault threshold value, processor 14 will follow the second differencevalue to adjust the first next data; on the contrary, when the seconddifference value is larger than the default threshold value, processor14 will follow the first difference value to adjust the second nextdata.

In addition, in practical application, rotational center O will notnecessarily be in between first location A and second location B. Forexample, please refer to FIG. 3 to FIG. 5, which illustratesrespectively different rotational situations in target object 2.

As shown in FIG. 3, target object 2 could be still and not rotational,at this moment, a_(T1)=−a_(T2), and Δθ₁ and Δθ₂ are both 0. As shown inFIG. 4, rotational center O might be on first location A, at thismoment, a_(T1)=0, and r₂=D; on the contrary, when the rotational centerO is at second location B, a_(T2)=0, and r₁=D. Furthermore, as in FIG.5, rotational center O might fall out of the line connecting firstlocation A and second location B (closer to first location A), at thismoment, r₁′=|r₁|, and r₂=D+r₁.

Therefore, in practical application, processor 14 can store in advancedata related to the above mentioned special situation; meanwhile, whenthe receiving sensors 10, 12 measure some data, it will compare with thepre-stored data so as to reduce the calculation time. For example, whenprocessor 14 receives both zero data of tangential acceleration (a_(T1),a_(T2)) from sensors 10 and 12, we can judge that target object 2 isstill and does not rotate. Furthermore, when 14 receives zero of firsttangential acceleration(a_(T1)) as sent from first sensor 10, and notzero of second tangential acceleration(a_(T2)) from second sensor 12, wecan judge that rotational center O is at first location A, hence, it isonly necessary to follow the data sent from second sensor 12 tocalculate rotational angle.

Theoretically, before the start of rotation or after the completion ofrotation of target object 2, processor 14 will follow the data sent fromsensors 10 and 12 to calculate, and the obtained rotational angles oftarget object 2 should all be zero. However, in practical application,even if target object 2 does not rotate, sensors 10 and 12 can stillsense the change of centrifugal acceleration or tangential acceleration.

Therefore, in actual application, only when first centripetalacceleration and/or first tangential acceleration, and/or secondcentrifugal acceleration and/or second tangential acceleration is largerthan default threshold value for preset time (For example, but notlimited to, continuous 0.1 second) (it represents the start ofrotation), processor 14 will calculate angular velocity, angularacceleration and rotational angle. But when first centripetalacceleration and/or first tangential acceleration, and/or secondcentrifugal acceleration and/or second tangential acceleration issmaller than default threshold value for preset time (For example, butnot limited to, continuous 1 second)(it represents the stop of therotation), processor 14 will not calculate. In practical application,processor 14 can still follow the obtained rotational angle of thetarget object 2 to output the control signal.

For further step, please refer to FIG. 6. FIG. 6 illustrates thefunctional block diagram of a portable device 3 of one preferredembodiment according to this invention. As shown in the figure, portabledevice 3 can include the above mentioned rotation measuring module andthe components such as first sensor 10, second sensor 12 and processor14 within it so as to measure the rotation of portable device 3. Inactual application, portable device 3 can further include othercomponents of the above mentioned rotation measuring module 1. Ofcourse, portable device 3 can also include other functional components,for example, screen, keys, network module, camera module and positioningmodule, etc. In addition, portable device 3 can execute program thatneeds to perform control through the rotational angle related data asmeasured by rotation measuring module 1, for example, but not limitedto, game and multi-media playing program, etc. At this moment, processor14 can further output rotational angle and other related data so as tocontrol the operation of those programs. In real application, processor14 can be integrated with the processing module of the portable device 3itself or it can exist independently.

To sum up, in this invention, two sensors are used to measurerespectively centrifugal acceleration and tangential acceleration ofdifferent locations of target object, hence, the rotation of targetobject in the horizontal direction can be measured. In addition, thedata measured by two sensors, depending on the real situation, cancompensate each other, and the error can be reduced. In addition, inthis invention, through the use of two sensors, the objective of themeasurement of rotation of target object in the horizontal direction canbe achieved, hence, it can be integrated within portable device so thatas compared to the prior art technology, it has advantages such as:small volume, low cost and low calculation complexity.

Although the present invention is disclosed through a better embodimentas above, yet it is not used to limit the present invention, anyone thatis familiar with this art, without deviating the spirit and scope of thepresent invention, can make any kinds of change, revision and finishing;therefore, the protection scope of the present invention should be basedon the scope as defined by the following attached “what is claimed”.

1. A rotation measuring module is used to measure the rotation of atarget object, and the rotation measuring module comprises of: a firstsensor, installed at one first location of the target object so thatwhen the target object is rotating, it can sense a first centripetalacceleration and a first tangential acceleration; a second sensor,installed at a second location of the target object so that when targetobject is rotating, it can sense a second centrifugal acceleration and asecond tangential acceleration; and a processor, which is connectedrespectively to the first sensor and the second sensor so as to receivefrom the first sensor the first centripetal acceleration(a_(C)) and thefirst tangential acceleration(a_(T)), and to receive from the secondsensor the second centrifugal acceleration and the second tangentialacceleration; meanwhile, the processor follows the following equation 1and 2 to calculate respectively the angular velocity (ω) and the angularacceleration (α) of the first location and the second location:$\begin{matrix}{\omega = \sqrt{\frac{a_{C}}{r}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\{\alpha = \frac{a_{T}}{r}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$ Wherein, r is respectively the distance from the firstlocation and the second location to the rotational center of the targetobject, next, the processor will follow the following equation 3 tocalculate a rotational angle (Δθ) of the target object: $\begin{matrix}{{\Delta \; \theta} = {{{\omega \cdot \Delta}\; t} + {\frac{1}{2}{\alpha \cdot \Delta}\; t^{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$ Wherein Δt is the sampling period of the first sensor andthe second sensor during the measurement.
 2. The rotation measuringmodule of claim 1 wherein the processor will follow respectively thefollowing equation 4 and 5 to calculate the distance (r₁) between thefirst location and the rotational center of the target object and thedistance (r₂) between the second location and the rotational center ofthe target object: $\begin{matrix}{r_{1} = \frac{D \cdot a_{{T\; 1}\;}}{a_{T\; 1} + a_{T\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack \\{r_{2} = \frac{D \cdot a_{T\; 2}}{a_{T\; 1} + a_{{T\; 2}\mspace{11mu}}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$ Wherein a_(T1) is first tangential acceleration, a_(T2) issecond tangential acceleration, and D is the distance between the firstlocation and the second location.
 3. The rotation measuring module ofclaim 1 wherein it further includes at least one low pass filterdisposed respectively among the first sensor and the second sensor andthe processor.
 4. The rotation measuring module of claim 1 wherein thefirst sensor, on at least two different time points and at the firstlocation, will sense a first previous data and a next data, and thesecond sensor, on the at least two different time points and at thesecond location, will sense a second previous data and a second nextdata, and the processor will then compare a first difference valuebetween the first previous data and the first next data, and thencompare a second difference value between the second previous data andthe second next data; wherein when the first difference value is largerthan one preset threshold value, the processor will then follow thesecond difference value to adjust the first next data, or when thesecond difference value is larger than the preset threshold value, theprocessor will then follow the first difference value to adjust thesecond next data.
 5. The rotation measuring module of claim 1 whereinonly when the first centripetal acceleration and/or the first tangentialacceleration, and the second centrifugal acceleration and/or the secondtangential acceleration is larger than the preset threshold value forthe preset time, processor will then calculate the angular velocity, theangular acceleration and the rotational angle.
 6. The rotation measuringmodule of claim 1 wherein the processor will follow the rotational angleto output a control signal.
 7. A rotation measuring method, which isapplicable to the measurement of the rotation of a target object, andthe rotation measurement method comprises of the following steps: (a)When the target object is rotating, at one first location of the targetobject, a first centripetal acceleration and a first tangentialacceleration will be sensed, and at the second location of the targetobject, a second centrifugal acceleration and a second tangentialacceleration will be sensed; (b) The first centripetalacceleration(a_(C)) and the first tangential acceleration(a_(T)), andthe second centrifugal acceleration and the second tangentialacceleration will be received respectively; (c) According to thefollowing equation 1 and 2, the angular velocity (ω) and angularacceleration (α) of the first location and the second location will becalculated respectively: $\begin{matrix}{\omega = \sqrt{\frac{a_{C}}{r}}} & \left\lbrack {{Equation}\mspace{14mu} 1} \right\rbrack \\{\alpha = \frac{a_{T}}{r}} & \left\lbrack {{Equation}\mspace{14mu} 2} \right\rbrack\end{matrix}$ Wherein, r is respectively the distance from the firstlocation and the second location to the rotational center of the targetobject; and (d) According to the following equation 3, one rotationalangle (Δθ) of the target object is calculated: $\begin{matrix}{{\Delta\theta} = {{{\omega \cdot \Delta}\; t} + {\frac{1}{2}{\alpha \cdot \Delta}\; t^{2}}}} & \left\lbrack {{Equation}\mspace{14mu} 3} \right\rbrack\end{matrix}$ Wherein At is the sampling period of the first sensor andthe second sensor during the measurement.
 8. The rotation measuringmethod of claim 7 wherein it further includes the following steps: (e)The following equation 4 and 5 are based respectively to calculate thedistance (r₁) between first location and the rotational center of thetarget object and the distance (r₂) between the second location and therotational center of the target object: $\begin{matrix}{r_{1} = \frac{D \cdot a_{T\; 1}}{a_{T\; 1} + a_{{T\; 2}\;}}} & \left\lbrack {{Equation}\mspace{14mu} 4} \right\rbrack \\{r_{2} = \frac{D \cdot a_{T\; 2}}{a_{T\; 1} + a_{T\; 2}}} & \left\lbrack {{Equation}\mspace{14mu} 5} \right\rbrack\end{matrix}$ Wherein a_(T1) is first tangential acceleration, a_(T2) issecond tangential acceleration, and D is distance between the firstlocation and the second location.
 9. The rotation measuring method ofclaim 7 wherein it further includes the following steps: (f) On at leasttwo different time points and at the first location, first previous dataand first next data is sensed, and a first difference value between thefirst previous data and the first next data is compared; (g) On at leasttwo different time points and at the second location, a second previousdata and a second next data is sensed, and a second difference value iscompared between the second previous data and the second next data; and(h) When the first difference value is larger than a preset thresholdvalue, the second difference value is based to adjust the first nextdata, or when the second difference value is larger than the presetthreshold value, the first difference value is based to adjust thesecond next data.
 10. The rotation measuring method of claim 7 whereinwhen the first centripetal acceleration and/or the first tangentialacceleration, and the second centrifugal acceleration and/or the secondtangential acceleration is larger than the preset threshold value forpreset time, steps (c) and (d) will be performed.
 11. A portable devicecomprises of the rotation measuring module of claim 1, which is used tomeasure the rotation of the portable device.
 12. The portable device ofclaim 11 wherein the processor will follow the rotational angle tooutput a control signal.